Peri-operative Ventilatory Management of Patients with Spinal Muscular Atrophy: Conditions for a Successful Outcome

Summary: Scoliosis associated with Spinal Muscular Atrophy (SMA) is often complicated by a significant reduction in pulmonary function which is usually restrictive in nature. The pre-operative and latest vital capacities were reviewed for 78 patients having undergone surgical correction of their spinal deformity. Severe restrictive lung disease is not a contraindication to undergo surgical correction of spinal deformities in SMA.

Introduction: Scoliosis associated with Spinal Muscular Atrophy (SMA) is often complicated by a significant reduction in pulmonary function. The perioperative ventilatory management remains a challenging clinical problem.

Methods: Retrospective review of 78 patients with SMA having undergone surgical correction of their spinal deformity. All patients underwent posterior spinal fusion performed by the same surgeon. Thirty-three patients underwent a complementary anterior spinal fusion. Chart review, pulmonary function tests and anesthesia records were reviewed for all patients. Vital capacity (VC) was evaluated pre-operatively and at the latest follow-up visit. Number of days ventilated and tracheostomy status pre- and postoperatively was noted.

Results: Complete data was available for 72 of 78 patients. The mean pre-operative VC was 1.16+/- 0.72 liters and the latest post-operative VC was 1.079+/-0.70 liters. Sixteen patients had a VC of less than 500cc's. Intubation period ranged from 0 to 26 days with a mean of 8.4+/-6.8 days. Patients with VC less than 1000 cc's had a significantly longer intubation time (10.4+/-6.3 days) compared to patients with greater VC (6.6+/-6.4; p=0.025). Thirteen patients had a tracheostomy pre-operatively. One patient needed to have a tracheostomy performed post-operatively for tracheal stenosis and one patient had her tracheostomy closed several months following surgical correction. There were 4 episodes of atelectasis, 5 pneumonias, one patient developed ARDS and one patient died because of tension pneumothorax.

Discussion: The pre-operative pulmonary status of patients with SMA does not preclude surgical correction of their spinal deformity. These patients need to be carefully evaluated pre-operatively and their VC optimized with breathing exercise and intermittent ventilatory support. Post-operatively, in the acute phase, mechanical ventilation until pre-operative vital capacity is regained permits safe extubation and limits pulmonary complications.

Conclusion: Severe restrictive lung disease is not a contraindication to undergo surgical correction of spinal deformities in SMA.